To get a good idea / result of where a niche could be open to you, it is best to use a sample of 20 – 40 businesses. Next to each of these businesses write down the main focus and then put these focuses into a variety of groups, i.e. one category may be quality and under this you may have premium or superior quality. Usually you will see that a specific industry will only be branding itself in 5 - 10 different ways.
Once you have categorised your list, you will then see what area isn’t catered for as much. The next step then is to work out what can you offer to this niche category and is it a viable option? Most of the time you will find that if you can separate yourself from the rest you are then in control of this particular brand strategy.